help -need a list of practising doctors in gisborne during 1964

help -need a list of practising doctors in gisborne during 1964

My husband has recently been told his birth mother(now dead) had another child - a 1/2 sister who was adopted out to a doctor with an unusual surname who lived in Gisborne in 1964. We have no surname to start our search for her yet, but would appreciate if anyone out there has access to a list of practising doctors in the area around that time.thanksKeira